Conventionally known is an autonomous underwater vehicle (hereinafter may be referred to as an “AUV”) which does not require electric power supply from a mother ship and sails in water by a built-in power source for seabed work, seabed investigation, and the like. PTL 1 discloses an AUV underwater base for charging the AUV in water without lifting the AUV to the mother ship.
The underwater base of PTL 1 is configured such that: a base mount is provided on the seabed; a seating base configured to be rotatable about a center axis extending in a vertical direction is provided on the base mount; and a signal transmitter used when the AUV measures the position of the underwater base and a connector connected to the AUV seated are provided at the seating base. Further, the underwater base is provided with a direction stabilizing fin by which the seating base is directed to a water flow direction by water flow. With this, the seating base is directed to the water flow direction at all times. Therefore, the AUV can always sail toward and seat on the seating base in a posture directed to an upstream direction, such posture being stable in terms of machine body control.